Sufficient caution is necessary when handling radioactive materials.

This rock is radioactive, so care must be taken when handling it.

Radon is a colorless, odorless gas that is a naturally occurring radioactive substance.

This new detergent is completely odorless.

This diamond is completely colourless, which is very rare.

What is this gas?

His existence enriches my life.

You can feel his presence.

Education about sex is very important.

What is this material made of?